The present invention relates to a display device capable of displaying images (video images) such as moving images by arranging a large number of thin gas discharge tubes with a discharge gas sealed therein.
Plasma displays (PDP) are practically used as thin, large-screen next generation displays. In a PDP, discharge is caused in a very small closed space, and ultraviolet radiation (wavelength: 147 nm) emitted by the discharge excites a phosphor layer and is converted into visible light. A large display device using this light-emitting principle of PDP is proposed, which is capable of displaying video images such as moving images by arranging a large number of gas discharge tubes, each of which is produced by providing a phosphor layer inside a thin glass tube with an external diameter of 1 mmφ and a thickness of 0.1 mm, for example, and sealing a discharge gas therein (see, for example, Japanese Patent Application Laid Open No. 2003-92085). Since this display device is a self emission type display device, it is possible to display bright video images and realize a large screen more than 100 inches without increasing the manufacturing facilities, manufacturing processes and cost. Thus, this display device is suitable for applications where the entire surface of an indoor wall is made a display device.
FIG. 10 is a schematic perspective view showing one example of a conventional display device using gas discharge tubes. FIG. 11 is a plan view showing essential sections, and FIG. 12 is a structural cross sectional view along the XII-XII line of FIG. 10. Note that a part of components are not illustrated in FIG. 11 to facilitate understanding. A conventional display device 80 comprises a large number of red gas discharge tubes 90a, green gas discharge tubes 90b, and blue gas discharge tubes 90c arranged in a direction orthogonal to the axial direction thereof, and a rear support body (substrate) 96 and a front support body (substrate) 98 sandwiching the respective gas discharge tubes between them. On the gas discharge tube-side surface of the rear support body 96, address electrodes (also called selection electrodes) 97, 97, . . . are disposed along the axial direction of the gas discharge tubes 90, while on the gas discharge tube-side surface of the front support body 98, sustain electrodes (display electrodes) 99, 99, . . . (each of which is composed of a pair of 99a and 99b) are disposed at predetermined intervals in a direction crossing the address electrodes 97 on the same level.
Each of the gas discharge tubes 90a, 90b and 90c is made of a thin transparent insulating tubular body, for example, a translucent glass tube 91 in the form of a cylinder with an internal diameter of 0.8 mm and a thickness of 0.1 mm. Formed on the inner surface of each glass tube 91 is a secondary electron emitting film (protective film) 92 for decreasing a voltage (discharge voltage) necessary for causing discharge. A phosphor support member 93 with an axial cross section in the shape of a crescent is disposed inside the glass tube 91, and a phosphor layer 94, which is to be excited by ultraviolet radiation produced by discharge to emit light, is formed on the inner surface of the phosphor support member 93. The phosphor layer 94 is made of a phosphor that emits light of a predetermined color for each gas discharge tube 90a, 90b, 90c. Moreover, a discharge gas 95 such as Xe—Ne and Xe—He is sealed in the glass tube 91.
First, by using either of the sustain electrodes 99a and 99b as a scanning electrode and applying a voltage between the scanning electrode and the address electrode 97, address discharge (counter discharge) for writing display data is selectively caused, and wall charge is produced on the inner wall of glass corresponding to the discharge cell. Subsequently, a voltage is applied between a pair of sustain electrodes 99a and 99b to cause display discharge (surface discharge) for retaining the display in the cell in which wall charge is produced by the address discharge. With this discharge, collision with Xe in the discharge gas occurs, and ultraviolet radiation is emitted. The ultraviolet radiation excites the phosphor layer 94, and is converted into visible light and emitted outside. Therefore, as shown in the plan view showing essential sections of FIG. 11, a region partitioned by the intersecting address electrodes 97 and the sustain electrodes 99a, 99b makes a unit light emission region (cell), and the resolution is determined based on the pitch V of a pair of sustain electrodes 99 and the pitch H of the addles electrodes 97.
By the way, in a display device as described above, a blue phosphor has lower excitation efficiency compared to a green phosphor and a red phosphor, and consequently there is a problem that the blue phosphor has insufficient luminance and causes a low color temperature. Hence, a display device was proposed to realize a desired color temperature by adjusting the color temperature by varying the width of the phosphor support member, depending on each emission color (see, for example, Japanese Paten Application Laid Open No. 2003-272562).